Currently, the Institute of Electrical and Electronic Engineers (IEEE) is drawing up a standard 802.11ax of a next-generation wireless local area network (WLAN). An orthogonal frequency division multiple access (OFDMA) technology will be introduced into 802.11ax. The OFDMA technology allows an access point (AP) to perform multiuser transmission with a plurality of stations (STA) at the same time. Therefore, a trigger frame needs to be defined. The trigger frame is sent by an AP, and is used to perform resource indication for uplink multiuser transmission. After receiving the trigger frame, a plurality of STAs send an uplink frame almost at the same time based on resource scheduling information in the trigger frame.
It has been determined that a trigger frame structure shown in FIG. 1a is adopted in a draft standard. The trigger frame is a Media Access Control (MAC) frame including a MAC frame header (MAC header), a frame body, and a frame check sequence field. The frame body may carry different MAC functions, such as channel detection, a block acknowledge request (BAR), or Multiple User-Request to Send (MU-RTS). Specifically, as shown in the figure, the frame body includes a common area and a per station area. The common area includes resource indication information that needs to be read by all STAs, and the per station area includes resource indication information that needs to be read by each STA.
In an actual application scenario, generally, an STA needs to respond, based on a MAC function carried in a trigger frame, with a MAC frame of a type corresponding to the MAC function; for example, the STA responds with a block acknowledge (BA) frame or an acknowledge (ACK) frame. In the prior art, a trigger frame type indication that is used to represent a MAC function carried in the trigger frame is added to the trigger frame, so as to indicate usage of the trigger frame, and send, based on the usage, corresponding MAC function information when trigger information is sent. As shown in FIG. 1b, FIG. 1b shows a trigger frame designed for multiuser detection. By introducing a trigger frame type into the trigger frame, different content is designed for trigger frames of different types. In addition to carrying trigger information, the common area and the per station area carry MAC function information. Each STA may obtain an uplink transmission resource based on the trigger information, and may respond, based on the MAC function information, with a MAC frame corresponding to a MAC function carried in the trigger frame.
However, a disadvantage in the prior art is that information received by each STA needs to include both trigger information and MAC function information, and each STA needs to respond, based on a trigger frame type indication, with a MAC frame of a corresponding type based on the MAC function information. This leads to a limitation, because some STAs may not need to respond with a MAC frame of a corresponding type.